Help with 2859 prop pitch ok?-gctid818654

[Ssjustaddwater]

Info

2003 2859 with brovo ll and 350 mag. Boat bottom is clean.

Does my rpm and boat speed seem correct?

My wife and I run out to the Channel Islands Nationl Park on the weekends. It's about a 25mi trip out to anchor up for the night. Boats full with water, diving gear, food, fuel, etc. Total fuel used out and back is always just under 60gal

I'm running at 3,900/4K rpm to be on top and cruz speed is around 17kt. Does this sound correct? Would be nice to lower RPM and still run at same speed?

Thanks

[SomeSailor]

Your cruise speed seems a bit low. At 3900RPM my 2859 would be right at 30MPH. I would run between 3600-3900 to get my best MPG on Floscan. It would vary a little around those numbers, but about 13-14GPH at that speed and was my most economical speed on plane.

[aluxury1]

My prop on the bravo 2 is 18 1/2 X 19 pitch. You may need to check your outdrive gear ratio. Whatever the case, you have bottom growth and or need to go up in pitch. 3200 is 22mph

[aluxury1]

at 17 kt. are you on plane?

[Jeffw]

I had a 2008 289 with 350 mag (300 hp) Bravo 3. If I recall, at 3800 rpm I was doing 28-30 mph.

[Chief_Alen]

Here is a list check it off one by one, something might not be right.

Engine Won't Reach Operating RPM. Check...

This is a generic list you don't have a carb: for example.

1. Fuel condition. Type and Octane possibly old fuel.

2. Propeller pitch or diameter, damaged blades. Wrong prop ...

3. Restricted fuel pickup tube or anti siphon valve Fuel System Test

4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse

5. Marine growth on hull and outdrive.

6. Wrong gear ratio in outdrive.

7. Restricted carburetor air intake (clogged flame arrestor).

8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive.

9. Poor cylinder compression Compression Test.

10. Carburetor defective, or wrong type.

11. Fuel pump pressure and vacuum

12. Boat overloaded, improperly loaded, or improperly trimmed.

13. Engine Overheating.

14. Engine timing and ignition system operation. Plugs, wires, etc.

14A- Check the dist. shaft some have a c-clip some don't, wiggle the shaft.

15. Remote control cables and linkage for proper travel to open throttle plates fully.

16-Valves need adjusting.

17-Hidden water in the hull.

Above copied and pasted from another website: #16 and #17 added by myself.

When I am asked to check wot on friends boats, I make sure the tank is half full, engine freshly tuned up.

Hull must be clean, doesn't help when the guy say's oh yea 3-5 weeks ago, nope freshly cleaned hull.

You have water tanks, 8.34 pounds per gallon of water. You do the math. That's fresh water, saltwater more.

[Ssjustaddwater]

Bottom is clean as it comes off the trailer.

On plane : Yes at 15kts the boat seems to wallow on plane but at 17kts it's smooth and flat on plane

So it sounds like a prop for brovo ll going up a pitch will lower my RPM

18 1/2 X 19 pitch is on it now, so what would be the next size up?

Does anyone have a pitch up they would like to offer up or a good place to buy one?

Thanks as always!

[Ssjustaddwater]

"aluxury1" post=818751 wrote:
at 17 kt. are you on plane?

Yes

[aluxury1]

What is the Wide open throttle RPM? Normal operating range 4800 to 5200 and rev limiter is 5600. If you aren't reaching 4800 rpm, you will need to go down in pitch. Even at 4800 you could go down by 4" in pitch and theoreticly still be in recommended range. Also, what is the position of your trim tabs? Check your prop to WOT range first then maybe some other ideas below.

Here are some suggestions I don't know if they will help though.

Have you checked your ignition timing?

Has the engine thrown any codes?

Anything stuck in the filter/intake?

Blocked exhaust? Water routing wrong.

Thermostat stuck open? Is the engine running up to temp.

Temp sensor on engine thinking engine is cold. Maybe a sensor is not connected wire fell off.

Leaky gasket causing a little bit of water into engine.

Blocked fuel filter.

Is it running on all cylinders? Maybe you have a faulty lead.

Was the drop in performance immediate? Or did it slowly get worse over time?

[SomeSailor]

I don't think you can go up anymore with a 350. That's a heavy boat and with the 5.7 you really need to spin them fast.

I'd get it tuned, new distributor cap, plugs, wires, etc and see if it winds up better. Old gas is a problem too. You don't need special high octane fuel, but stale isn't good either.

[KPS]

If you are getting those RPMs and only getting 17kts, I would think the prop has spun. A 19p prop on your B2 should push you at upper 20's at rpm. I didn't see that suggested, but it could be your prop hub is shot.